Rolling Reload of NonStop Kernel Processors

Rolling Reload of NonStop Kernel Processors 2/18/04
Hewlett-Packard Development Company L.P. 2 of 7 CSSI Website
2 Planning a rolling reload.
Rolling reloads are significant system events and require careful planning. The first step
is to gather and evaluate all documentation pertaining to the planned update, such as SPR
documentation or Hotstuff messages. The Global Customer Support Center (GCSC) is an
excellent resource for rolling reload assistance. Contact the GCSC after completing a
rolling reload plan. They can provide assistance with specific NonStop products that
might be involved with or affected by the rolling reload. GCSC might also be able to
provide information based on the experience of other customers who have installed the
planned update using a rolling reload.
The remainder of this section identifies specific topics to consider when planning a
rolling reload.
2.1 Verify fault-tolerant applications (including recovery)
Make sure that your application can tolerate and recover from sequential halts of different
processors. Some applications can recover from a single processor halt but may have
difficulty with repeated halts. Also make sure that your application can recover and
rebalance when the processor is reloaded. Consider the recovery of cluster-based and
Expand-based applications, and the potential impact on applications that use the Remote
Duplicate Database Facility (RDF).
2.2 Choose the processor reload sequence
Unless there are specific reasons for choosing a different reload sequence, rolling reloads
should update all even processor numbers first and then update all odd processors. This
strategy provides extra time for even-odd process pairs to recover from processor halts
and reloads. If the primary and backups for key operating system and application
processes are not assigned to even-odd processor pairs, consider changing the order of the
rolling reloads to separate the reloads of the processors or processes configured as pairs
as much as practical.
2.3 Select rolling reload date and time
Choose a time in the day, week, or year when the system utilization is expected to be at
its minimum. Even if your applications work in the presence of single processor halts and
will fully recover after a processor halt, verify that no processor is utilized more than 45
percent before beginning the rolling reload.
2.4 Determine which processors need to be reloaded
Review previous software and firmware installations. The change being installed by the
rolling reload might already be completed on some processors, for example, a processor
that was reloaded using the new software due to a processor halt. Only reload the
processors that must be updated with new software.
2.5 Determine how much time is required for a rolling reload
The time required for a rolling reload is the sum of the time to (1) halt each processor
with a complete takeover by backup processes, (2) apply the change to each processor,